A unitary authority is a term used in a two-tier local government system to describe a unit of local government that operates as a single tier.
In New Zealand a unitary authority is a territorial authority (district or city) which also performs the functions of a regional council. New Zealand has four unitary authorities: Gisborne District, Nelson City, Tasman District and Marlborough District. The Chatham Islands Council is not usually considered a unitary authority, although it is considered a regional council for the purposes of the Resource Management Act.
More commonly referred to as single-tier municipalities, they exist as a single level of government in a province that otherwise has two levels of local government. One should not confuse municipalities in provinces with no upper-level of local government as single-tier municipalities, as these are the only level of local government in that province.
Structure of a single-tier municipality varies, and while most function as cities with no upper level of government, some function as counties or regional municipalities with no lower municipal subdivisons below them. The vast majority of Canadian single-tier municipalities are located in Ontario, where they exist as individual census divisions, as well as seperated municipalities.
The term 'unitary authority' itself first surfaced in the Redcliffe-Maud Report, to describe the sort of authority the report recommended cover most of England. These sorts of authorities already existed and were called county boroughs; but the term was urban in character. The Report was rejected by the incoming government after the 1970 general election, and county boroughs were abolished in 1974. It was not until the 1990s that unitary authorities would be created in the UK.
Creation of unitary authorities
Unitary authorities can be created by statutory instruments, so do not require separate legislation, under the terms of the Local Government Act 1992. Typically a district of an administrative county is designated as a new administrative county, but without a county council. The borders of the original county are adjusted to exclude the unitary authority area. In common usage unitary authority areas are not usually referred to as counties, although there are exceptions such as the Herefordshire and Rutland, which are reinstatements of counties lost in the 1974 reorganisation; and the Isle of Wight, (the first Unitary Authority created after the 1992 Act, and arguably one of the simplest and least controversial to create) which was, and remains, a separate county, but now with only a single council.
In some cases, such as the boroughs of metropolitan counties and Berkshire a different process was followed, where the county council was abolished, and its functions merely transferred to the districts.
Scotland and Wales consistently use unitary authorities. They have been becoming common in England since the 1990s. However the two-tier arrangement (increasing to three-tiers, for the remaining county administrations) has remained in a different form due to the introduction of a regional level of administration.
London boroughs (including the City of London), the Isles of Scilly, are also counted as unitary authorities.
Listings of unitary authorities in England can be found by region, or in Subdivisions of England.